That again depends on the DM, and I have found a couple who will allow it.
I only go that route though when I'm in a game that screams for cheesy

Everything in the game "depends on the DM". If the DM okays my homebrew "Kill everything instantly and manifest bitches who love me." ability, should I tell everyone I'm great at optimization because I found a combination that would let me kill everything instantly and manifest bitches who love me?

Homebrew and optimization should never even be near each other on a shelf at the supermarket.

Any GM that allows two obviously overpowered homebrew traits that do the exact same thing just because they have different names needs his head examined. Size increase isn't a remotely balanced trait anyhow. And the Overcompensation flaw isn't. A flaw that is. It might fly as a trait, albeit another overpowered one, but it doesn't even begin to be a flaw. Same with Big Dumb Bruiser. Obviously written by people who don't understand what Flaws are.

Monkey grip isn't even close to resembling overpowered. 'I constantly power attack for two points, and in return I get crippled on my magic item rewards', and exotic weapon proficiency is identical in that 'I get slightly more powerful in return for being crippled in the possible magic item rewards I can get'.

The only reason one would ever pick up the feats is for concept, or if you were picking up a particularly common exotic weapon like the bastard sword or spiked chain (not that the former is worth it anyway), or if you were small sized and wished to use medium weapons, etc.

Edit: Also, in that build (the traits and flaws are all ridiculously unbalanced), you don't even need monkey grip, you could wield a colossal weapon without it, you want a EWP (Heavy fullblade) instead so your damage actually becomes 12d8. If you're going for super broken, do it right man!

I feel dumb now, I talked about as if you were calling monkey grip overpowered and I apologize.